1. Field of the Invention
The present invention relates to a stereo image forming apparatus, and more particularly to a stereo image forming apparatus for enabling, in observing a stereo image (for example, with television images obtained by two television cameras mutually distanced by a predetermined base line), observation of a satisfactory stereo image easily and promptly over the entire distance range from an infinite distance to a very short distance, by a simple method.
2. Related Background Art
Conventionally, observation of a stereo image has been achieved by placing two image taking systems with a mutual distance of the optical axes thereof corresponding to the distance of the eyes (parallax or base line length) of the observer, and observing two images obtained by said two image taking system respectively with left and right eyes.
FIG. 5 is a schematic view of a conventional stereo image forming apparatus for observing a stereo image with television images.
Television cameras 51, 52, respectively corresponding to the right and left eyes of the observer, are rotatably positioned with a mutual distance corresponding to a predetermined base line length.
Television receivers 53, 54 respectively corresponding to the television cameras 51, 52 provide slightly different images with a parallax. There are also shown polarizing filters 55, 56 with mutually perpendicular polarizing directions; a half mirror 57; polarizing glasses 58 in which the polarizing direction of a polarizing filter 58a for the right eye is parallel to that of the polarizing filter 55 while the polarizing direction of a polarizing filter 58b for the left eye is parallel to that of the polarizing filter 56; an object 59 to be observed; and an observer 60.
In the illustrated stereo image forming apparatus, the left eye observes the image of the television receiver 54 only, while the right eye observes the image of the television receiver 53 only, by means of the polarizing filters, whereby the observer can observe a stereo image of the object 59 viewed by the television cameras 51, 52.
When the distance to the object varies, the two television cameras 51, 52 are rotated by unrepresented driving means in such a manner that the optical axes of the image taking system are directed to the object 59, as indicated by broken lines.
In the conventional stereo image forming apparatus as shown in FIG. 5, the television cameras are rotated by driving means in such a manner that the optical axes of the image taking systems are directed to the object when the distance thereof varies.
However the generally large weight of the television cameras requires a large driving force for rotating the television cameras corresponding to the change in the distance of the object. Also there is required a complex driving mechanism, and it is difficult to promptly and precisely rotate the television cameras.